You answer:

Well, there can be many reasons, breakdown of the gas boiler or low pressure in the gas boiler, well, I'm not a plumber so I can't say for sure. Even new equipment can break down, so it is better to go to the professionals to come and see what's wrong. It has to be related to something, radiators can't just stop heating because of a bad mood. Although maybe you just need to wait a while and everything will work, maybe there is some kind of resetting of the gas boiler.